Fennec nightly, do a one touch pinch on a bugzilla page. It remains blurry. Looks like the main thread doesn't take the new resolution, because pinching afterwards resets the zoom back to what it was before the one touch pinch.

Sometimes we can get empty transactions after a scrollframe is
layerized. In such cases the isLayerized check would incorrectly detect
the scrollframe as not being layerized because it would only look at the
data for the empty transaction.